Defense Environment Alert
February 26, 2002

ADDITIONAL ACWA TESTS LESSEN NRC CONCERNS OVER USE AT PUEBLO

Testing completed last year continues to demonstrate the effectiveness of two non-incineration technology destruction methods for chemical weapons, and the results alleviate some concerns a National Research Council (NRC) panel raised in a report last August, according to a recent letter from the panel to the Defense Department.

The NRC Committee on Review and Evaluation of Alternative Technologies for Demilitarization of Assembled Chemical Weapons: Phase 2, in a Feb.. I letter details five findings related to the possible use of the alternative technologies at the stockpile site in Pueblo, CO. The letter, sent to Nfichael Parker, program manager for DOD's Assembled Chemical-Weapons Assessment (ACWA) program, updates findings the committee made in an August 2001 report, which found the two technologies under consideration for use at Pueblo were able to destroy chemical agent but still faced several technical challenges (Defense Environment Alert, Sept. 11, 200 1, p 11). The letter is available on InsideEPA. com. Seepage 2for details.

The review comes not long before the Defense Department is slated to make a final decision on which destruction technology to use at Pueblo, and as public support for using a non-incineration destruction technology there is soaring. Another NRC panel recently released an updated report on the possible use of a modified incineration technology (see related story).

The two ACWA technologies are Parsons/Honeywell water hydrolysis of explosives and agent technology (WHEAT) and General Atomics total solution (GATS). Both use hydrolysis with water or caustic to destroy agents and energetics. WHEAT then applies a biotreatment to the resulting hydrolysates, while GATS treats hydrolysates with supercritical water oxidation (SCWO).

"In presenting this update, the ACW II Committee first reiterates its observation that hydrolysis with water or caustic does destroy 99.9999 percent of the chemical agent and, in combination with secondary treatment steps, 99.999 percent of the energetic materials," the Feb. I letter says. "The committee's concerns with regard to the two technology options being considered for Pueblo relate only to steps after and ancillary to the hydrolysis step."

Since the publication of the August 2001 report, the ACWA program has completed engineering design study (EDS) testing on hydrolysis of energetics. The purpose of the testing was to define process parameters, demonstrate safe processing for the scale-up of the hydrolysis process, and produce hydrolysates for future use in the ACWA program, NRC says. "The testing also addressed concerns raised by the NRC regarding processing, as well as issues encountered during previous energetics hydrolysis testing at other facilities."

The committee's first finding is that "[c]ompleted EDS test reports indicate that hydrolysis can safely destroy the energetic materials found in the assembled chemical weapons at Pueblo Chemical Depot." Some questions do reinain, the letter notes, but the problems can likely be solved.

For instance, not all of the lead in the munitions can be accounted for at the end of processing. "The difficulty of accounting for all the lead, combined with the observed generation of energetic intermediates during the course of the run, raises the possibility that lead picrate, a sensitive nitroaromatic explosive, might precipitate under some conditions." But as long as lead-containing propellant is processed separately from nitroaromatic compounds, this should not be a problem, the letter says.

The committee had been very concerned in its August report about the large number of liner changes that may be necessary for the SCWO system. While this is still a concern, the additional tests "indicate that far fewer SCWO reactor liner change-outs would be required at Pueblo than had been thought previously by the committee," the letter says. "It should be possible to restrict liner change-outs to no more than one every 2 or 3 weeks of operation when processing HD [mustard] hydrolysate. In the committee's opinion, this level of maintenance, while high, does not place an unmanageable burden on the operations and maintenance staff," the letter says later.

The committee says it still has some concerns about possible issues that might arise when the SCWO reactor is scaled up to actual size because it will increase problems with sealing and interchanging the interior assemblies during liner change-outs. "However, there does not appear to be a reasonable way of addressing this scale-up issue until a full-scale unit is built," the letter says.

In a third finding, the committee says it "now believes the technology [of cryofracture] has been sufficiently demonstrated for use at Pueblo." Cryofracture is the technology General Atomics developed for the Army from 1982 through 1993, and it would be used to open the munitions to access the agent for treatment.

With the Parsons WHEAT technology, "[t]he testing of the Parsons' projectile washout system indicates that a full-scale system can be satisfactorily designed, built, and operated," the letter says. "The tested system operated well during the tests, successfully removing all visible mustard agent residue from 85 4.2-inch mortars," it adds.

Finally, the committee says that tests of the continuous steam treater (CST) and its effluent gas treatment system using dunnage and demilitarization protective ensemble suit material have been completed. "Tests of the CST and the proposed improvements provide reasonable assurance that the CST can accomplish acceptable treatment of dunnage, provided that acceptable treatment of the gaseous effluent can be achieved," the letter says.